Add/Update list in database using Entity framework 6 - entity-framework

Question

I have three tables QuestionBank,Question and Answer. " QuestionBank " will have list of Question and " Question " will have list of " Answer ".
QUESTIONBANK :-
public class QuestionBank
{
public int id { get; set; }
public string Text { get; set; }
public string Chapter { get; set; }
public string Standard { get; set; }
public List<Question> Question { get; set; }
public QuestionBank()
{
this.Question = new List<Question>();
}
}
QUESTION :-
public class Question
{
public int id { get; set; }
public string Title { get; set; }
public string QuestionText { get; set; }
public List<Answer> Answer { get; set; }
public string CorrectAnswer { get; set; }
public Question()
{
this.Answer = new List<Answer>();
}
}
ANSWER :-
public class Answer
{
public int id { get; set; }
public string AnswerText { get; set; }
}
WEB API :- //Edited
private IRepository<QuestionBank> _QuestionBankRepository;
public QuestionController(IRepository<QuestionBank> QuestionBankRepository)
{
_QuestionBankRepository = QuestionBankRepository;
}
[HttpPost]
[Route("Ques/Add")]
public Boolean Add(QuestionBank AddQuetionBankData)
{
var isQuetionBankPresent = _QuestionBankRepository.GetAll(p => p.Text == AddQuetionBankData.Text && p.Standard == AddQuetionBankData.Standard && p.Chapter == AddQuetionBankData.Chapter).FirstOrDefault<QuestionBank>();
if (isQuetionBankPresent != null)
{
/* Add the data in Question and Answer tables */
return false;
}
else
{
/* Add the data in all three tables */
return true;
}
}
I have this database for the web api. Now I want to add the data in database through json { "QuestionBank": QuestionBank, "Question": Question, "Answer": Answer } if the row is present in QuestionBank i dont want to add that data in QuestionBank table and only add the data in Question and Answer table with respective foreign keys. I am using the entity frame work and mvc 5 web api. I am stuck at this point. Please if any thing is needed let me know. Thanks in advance.

Answer 1

The Entity Framework way to update is to to Context.Entry([your object]).State = System.Data.Entity.EntityState.Modified; providing that the object is of the right type.
public Boolean Add(QuestionBank AddQuetionBankData)
{
bool flag = false;
var question = this.MapToQuestion(AddQuetionBankData); //map the input to the EF Type Question
var anwer = this.MapToAnswer(AddQuetionBankData); //map the input to the EF Type Answer
var isQuetionBankPresent = _QuestionBankRepository.GetAll(p => p.Text == AddQuetionBankData.Text && p.Standard == AddQuetionBankData.Standard && p.Chapter == AddQuetionBankData.Chapter).FirstOrDefault<QuestionBank>();
if (isQuetionBankPresent != null)
{
_context.Entry(question).State = EntityState.Modified;
_context.Entry(answer).State = EntityState.Modified;
/* Add the data in Question and Answer tables */
flag = false;
}
else
{
_context.Entry(question).State = EntityState.Modified;
_context.Entry(answer).State = EntityState.Modified;
_context.Entry(AddQuetionBankData).State = EntityState.Modified;
/* Add the data in all three tables */
flag = true;
}
_context.SaveChanges();
return flag;
}
private Question MapTo Question(QuestionBank q) //do this for Answers too
{
var _q = _context.Question.Where(a=>a.Id == q.Id).SingleOrDefault();
if(_q!=null)
{
_q.id = q.id; //this is already true
_q.Title = q.Title;
_q.QuestionText = q.Standard; //I guess
}
return _q;
}
The EF updates the Entity (the class you pass to the method Entry()) accordingly to its Type.
Notice that the position of the SaveChanges(): it works like a stored procedure, you do all the updates and the SaveChanges() is like the SQL COMMIT command.
You should also wrap the SaveChanges in a try/catch to handle errors, and dispose the _context.
EDIT
This class has as dependency IRepository<Question>, IRepository<QuestionBank>, and IRepository<Answer>.
You should create an UpdateController(or PublishController or whatever) that gets the three dependencies in the constructor (better a Facade Service), and call the Add() method for each one of them.
If you access directly the raw Database object you could do like I did and use the Entry() method for each table.